[Insight-users] DICOM measures

Fri Dec 11 07:30:57 EST 2009

open your file in ITKsnap. In the file open dialog, it gives you all the
dimensions of x,y,z in number of pixels,
along with the image coordinates.

Write them down.

Then run example Examples/IO/DicomSeriesReadPrintTags.cxx.

It gives you the tags and the information contained in the tags.

You can then see which dimension corresponds to which tag.

Good luck!

Michael

On Fri, Dec 11, 2009 at 11:49 AM, l.a.pereira <l.a.pereira at uol.com.br>wrote:

> Hi Michael,
>
> Great sugestion. Can you say me what are this tags ?
>
> More one question: In the formule: (number of pixels along an axis) *
> (pixel size in mm)
> (slice thickness) * (number of slices), the variable (number of slices)
> just can find in the orietation axis (in my case axial), right ?
>
> If yes, how can i use this formule for all others orientation
> (coronal/sagital) ?
>
> Thanks,
>
>
>
> Em 11/12/2009 07:56, *michiel mentink < michael.mentink at st-hughs.ox.ac.uk>
> * escreveu:
>
>
> Hi Luis Pereira,
>
> If I understand correctly, you want to know how big the dicom volume is in
> mm.
> I think Luis has answered that already.
>
> However, I can give you a different answer, why don't you calculate
>
> (number of pixels along an axis) * (pixel size in mm)
> (slice thickness) * (number of slices) ?
>
> Those dimensions you can find in your dicom tags.
>
> Good luck,
>
> Michael
>
>
>
>
> On Wed, Dec 9, 2009 at 4:00 PM, l.a.pereira <l.a.pereira at uol.com.br<http://mce_host/compose?to=l.a.pereira@uol.com.br>
> > wrote:
>
>>
>> Luis, sorry i'm sending message again, I had problem with first email
>> format.
>>
>> Luis, thanks for reply.
>>
>> My problem is know how tags I need use to calculate original DICOM
>> dimensions x,y,z to milimeters.
>>
>> I believe that if I get the total physical extend image I will solve my
>> problem.
>>
>> My application read a DICOM series and create a Volume. After that, the
>> user will work from slices x,y,z obtained from
>>
>> vtkImagePlaneWidget->GetResliceOutput(), so I need to establish a
>> co-relation between vtkImagePlaneWidget->GetResliceOutput() and the
>>
>> original measures of DICOM Series in milimeters.
>>
>>
>>
>>
>>
>> Em 09/12/2009 13:27, Luis Ibanez < luis.ibanez at kitware.com<http://mce_host/compose?to=luis.ibanez@kitware.com>> escreveu:
>>
>>
>>  Hi Luis,
>>
>> Could you please be more specific regarding
>> what you call "measures"   ?
>>
>> Are you referring to the total physical extent of the image ?
>> (e.g. the volume of space that is occupied by the image).
>>
>> or are you referring to measuring distances between pairs
>> of pixels in the image ?
>>
>> If you are talking about the second case, then what
>> you want to do is to take the indices of  both pixels.
>> (let's call them index1 and index2) and do the following:
>>
>>
>> const ImageType * image = reader->GetInput();
>> ImageType::PointType point1;
>> ImageType::PointType point2;
>>
>> image->TransformIndexToPhysicalPoint( index1, point1 );
>> image->TransformIndexToPhysicalPoint( index2, point2 );
>>
>> const double distance = point1.EuclideanDistanceTo( point2 );
>>
>> That value of "distance" will be measured in millimeters,
>> which is the default unit in DICOM,
>>
>> When the indices are converted to physical points, the
>> computation process will take into account:
>>
>> A) The coordinates of the image Origin
>> B) The values of pixel spacing
>> C) The orientation (direction) of the image
>>
>> The resulting value of "distance" will therefore be
>> in the units of physical space.
>>
>>
>> As Michiel pointed out, the values of (A), (B) and (C)
>> are defined in the DICOM tags.   If you are curious
>> about the values, you could also print them out with
>>
>> reader->Update();
>> const ImageType * image = reader->GetInput();
>> std::cout << image->GetOrigin() << std::endl;
>> std::cout << image->GetSpacing() << std::endl;
>> std::cout << image->GetDirection() << std::endl;
>>
>>
>> ---
>>
>> If you were talking about other type of "measures",
>>  please, describe them i n detail.
>>
>>
>>
>> Thanks,
>>
>>
>> Luis
>>
>>
>>
>> ------------------------------------------------------------------------------------------
>> On Wed, Dec 9, 2009 at 8:13 AM, michiel mentink
>>  wrote:
>> > Hi Luis,
>> >
>> > try example Examples/IO/DicomSeriesReadPrintTags.cxx.
>> > It prints the most important tags.
>> >
>> > It is described in the itk software guide paragraph 7.12.6
>> > You can also see those tags summarized on my page on:
>> >
>> https://sites.google.com/site/michielmentink/programming/itk/image-translate
>> > (on the bottom).
>> >
>> > greets,
>> >
>> > Michael
>> >
>>  > On 12/9/09, l.a.pereira  wrote:
>> >>
>> >> Hi,
>> >>
>> >> I'm reading a DICOM series with GDCMImageIO.
>> >>
>> >> Now, I need obtain the measures of this DICOM series to convert it in
>> >> milimeters.
>> >>
>> >> How can I do it ?
>> >>
>> >> There is some tags in DICOM header where I can calculate/convert this
>> >> measures to milimeters ?
>> >>
>> >> Thanks,
>> >>
>> >>
>> >>
>> >> Luis
>> >>
>> >>
>> >>
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